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authorLinus Torvalds <torvalds@linux-foundation.org>2013-11-27 21:04:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-27 21:04:37 -0800
commitf496863658eac9054d4bd4c661774d76d83255e0 (patch)
tree897e967416a204e21d957386514559b2a07a2a9d
parentba33fef0f62a97e1faf285a5ee2bcad85622f4fd (diff)
parent81440e73744446adbe5b5d1f19460203d275028f (diff)
downloadlinux-linaro-stable-f496863658eac9054d4bd4c661774d76d83255e0.tar.gz
Merge tag 'driver-core-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core fixes from Greg KH: "Here are 3 patches for sysfs issues that have been reported. Well, 1 patch really, the first one is reverted as it's not really needed (the correct fix is coming in through the different driver subsystems instead) But that 1 sysfs fix is needed, so this is still a good thing to pull in now" Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> * tag 'driver-core-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: Revert "sysfs: handle duplicate removal attempts in sysfs_remove_group()" sysfs: use a separate locking class for open files depending on mmap sysfs: handle duplicate removal attempts in sysfs_remove_group()
-rw-r--r--fs/sysfs/file.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 79b5da2acbe1..b94f93685093 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -609,7 +609,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
struct sysfs_open_file *of;
- bool has_read, has_write;
+ bool has_read, has_write, has_mmap;
int error = -EACCES;
/* need attr_sd for attr and ops, its parent for kobj */
@@ -621,6 +621,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
has_read = battr->read || battr->mmap;
has_write = battr->write || battr->mmap;
+ has_mmap = battr->mmap;
} else {
const struct sysfs_ops *ops = sysfs_file_ops(attr_sd);
@@ -632,6 +633,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
has_read = ops->show;
has_write = ops->store;
+ has_mmap = false;
}
/* check perms and supported operations */
@@ -649,7 +651,23 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
if (!of)
goto err_out;
- mutex_init(&of->mutex);
+ /*
+ * The following is done to give a different lockdep key to
+ * @of->mutex for files which implement mmap. This is a rather
+ * crude way to avoid false positive lockdep warning around
+ * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
+ * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
+ * which mm->mmap_sem nests, while holding @of->mutex. As each
+ * open file has a separate mutex, it's okay as long as those don't
+ * happen on the same file. At this point, we can't easily give
+ * each file a separate locking class. Let's differentiate on
+ * whether the file has mmap or not for now.
+ */
+ if (has_mmap)
+ mutex_init(&of->mutex);
+ else
+ mutex_init(&of->mutex);
+
of->sd = attr_sd;
of->file = file;